The International Patent applications WO99/57118 and WO02/05616 describe 6-phenylphenanthridines as PDE4 inhibitors.
In the International Patent application WO99/05112 substituted 6-alkylphenanthridines are described as bronchial therapeutics.
In the International Patent application WO02/066476 benzonaphthyridine derivatives are described which have a guanidyl substituent.
In the European Patent application EP 0490823 dihydroisoquinoline derivatives are described which are useful in the treatment of asthma.
The International Patent application WO2004/018431 discloses 6-phenylphenanthridines as PDE4 inhibitors.
The International Patent application WO02/066476 discloses 6-phenylbenzonaphthyridines as PDE4 inhibitors.
The U.S. Pat. No. 6,476,0251 discloses 6-phenylphenanthridines as PDE4 inhibitors.
The U.S. Pat. No. 6,306,8691 discloses benzonaphthyridine N-oxides as PDE4 inhibitors.
The International Patent applications WO2004/019944 and WO2004/019945 disclose hydroxy-substituted 6-phenylphenanthridines as PDE4 inhibitors.